Hydrophone cable



May 17, 1955 w. T. HARRIS HYDROPHONE CABLE Filed April 22, 1952 ATTO/PNE?? HvnnoPHoNE CABLE Wilbur T. Harris, Southbury, Coun., assigner to The Harris Transducer Corporation, Southbury, Conn., a corporation of Connecticut Application April 22, 1952, Serial No. 283,689

14 Claims. (Ci. 340-4) My invention relates to electro-acoustic transducers and, in particular, to arrayed constructions thereof.

It is an object of the invention to provide an improved transducer array of the character indicated.

It is another objectto provide an improved underwater transducer array which may lend itself to electric steering.

It is a further object to provide an underwater transducer array which is substantially neutrally buoyant.

A still further object is to provide improved cabling means for underwater acoustic arrays.

It is a general object to meet the above objects with a rugged, integral cable-transducer construction which will lend itself to shipboard handling, as when necessary to pay the cable in and out.

Other objects and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification, in conjunction with the accompanying drawings. In said drawings, which show, for illustrative purposes only, preferred forms of the invention:

Fig. lis a simplified side view illustrating a surface vessel towing a payed-out length of hydrophonic cable incorporating features of the invention;

Fig. 2 is an enlarged fragmentary view in partial longitudinal section illustrating the hydrophonic cable of my invention;

Fig. 3 is a simplified diagram illustrating electrical connections for the cable of Fig. 2;

Fig. 4 is a diagram similar to Fig. 3, but illustrating an alternative connection;

Fig. 5 is an enlarged fragmentary view in partial longitudinal section, illustrating an alternative construction for a part of Fig. 2; and

Fig. 6 s another fragmentary view in partial longitudinal section, illustrating an alternative for another part of Fig. 2.

Brieiiy stated, my invention contemplates an improved electro-acoustic array comprising a plurality of electroacoustic devices integrally formed with the connecting cable. The electro-acoustic devices may be simply cylindrical or annular radially strictive members with means electrically responsive to radially strictive excitation of said members. The members may surround the cable at spaced locations depending upon the desired acoustic properties of the array. The cable may be of the multiconductor variety and have a flexible tension core, as of stranded steel. At the point of attachment of each transducer to the cable, pressure-release means may be provided of a su'icient volume to give the cable neutrality buoyant properties and, if desired, these properties may be enhancedby provision of annular floats integral with the cable at appropriate spacings. by employment of novel reinforcements and by using sound-transmitting'v potting materials of suitable toughness.

Referring to the drawings, I indicate generally in Fig. 1 that my array may comprise a plurality of transducer Ruggedness is achieved elements 10, spaced longitudinally along a single cable 1I, and suitably supported for the intended purpose. In the case shown in Fig. 1, the cable is to be employed for underwater oil-prospecting, and I show the cable 11 being payed out from a drum 12, supported at the stern of a towing vessel 13. The various hydrophones 10 on the cable 11 may themselves be suliiciently neutrally buoyant but, if desired, additional buoyancy may be provided by novel floats 14 spaced from the hydrophones 11. The float and hydrophone constructions are shown in greater detail in Fig. 2.

As will be seen from Fig. 2, the supporting cable 11 may be of the multi-conductor variety (as indicated schematically by spaced longitudinally extending lines 15) filling the annular space around a tension core 16, which may be a stranded-steel cable. For ready identification, the conductors 15 may be color-coded, and they may be immersed in a layer of insulating material 17; alternatively, the conductors 15 may be twisted as individual pairs, separately insulated, and merely packed around a plastic or rubber-coated stress core 16, the immersion in insulating material 17 being unnecessary in certain applications. A coating or jacket 18 completes the construction of the cable 11 itself.

The assembly of the cable 11 may in all respects be conventional except that I prefer, at each location where a hydrophone 10 is to be attached, that a different pair of conductors 15 (as, for example, the conductors 15 in Fig. 3) `be brought into a slightly enlarged loop for electrical connection to each particular hydrophone. This loop may be gathered and knotted externally of the liling `17 before application of the cover 18, so that when the cover 18 is applied, a small bump in the outer contour will show where incision must be made to gain access to the desired pair of conductors 15. The cover 18 may be of tough plastic, such as vinyl, but I prefer to use rubber or a rubber-like material, such as neoprene.

The hydrophone unit 10 is, in each case, preferably non-directional and, therefore,` small compared to a wave length. The basic transducer elements themselves preferably continuously envelop the cable 11, and I have shown annular radially strictive means 19 surrounding the cable 11 and slightly spaced therefrom. The annular member 19 may be of electro-strictive material, such as barium titanate, with inner and outer conductive foils constituting means electrically responsive to transient pressure excitation, as described in greater detail in my copending application, Serial No. 127,437, tiled November 15, 1949. However, in the preferred form shown, the annular member 19 is a hollow magneto-strictive cylinder, which may be of magneto-strictive ceramic, such as a ferrite (as described in my copending application, Serial No. 278,836, tiled March 27, 1952), but which I have indicated to be oflaminated-sheet magneto-strictive metal.

The means electrically responsive to pressure variations may be a t'oroidal winding 20 about the core 19. For a reason which will later become apparent, I prefer to provide the transducers in duplicate at each hydrophone unit 10 and, therefore, I show a second core 19' with a second toroidal winding 20 for the device 10. These windings 19*19 may be connected in series with each other ,j and across the looped conductor pair 15 at each point of connection to the cable, as suggested at Fig. 3.

It will be understood that the transducer elements 19-19 for the hydrophone unit 10 may be connected to'one pair of conductors in the cable 11, and that Vat another hydrophone-unit location the transducer windings thereof may be connected to the same pair or to a different pair of conductors, depending upon the desired overall performance of the device. When connected to different pairs of conductors at different hydrophone lo-.

Patented May 17, 1955' cations, it will be understood that the array may lend itself to phased steering at the shipboard-receiving location, by employment of means which are known and are, therefore, not shown.

In the specific construction of Fig. 2, the transducer means l92il is protected against abuse by means of a reinforcement'member 22 in the form of a cylindrical core, which may be of aluminum in order to reduce the density of the assembly, This core may be integrally formed with reinforcement flanges at spaced locations, or, as shown, rings 23-24 may be provided to ride on the cylinder 22. The rings 23--24 extend radially outwardly to an extent at least equivalent to the outer dimensionsr of the wound core 19-20, and preferably slightly beyond, as shown. The wound cores may then be potted with a sound-transmitting material 25 (auch as a suitable plastic) in the annular space defined between the reinforcement rings 231-24. I have shown a layer 25 of pressure-release material lining this annular space and riding on the outside of cylinder 2.2, so that the transducer means .t9- 20 may be primarily responsive to radial deformations due to external excitation.

After assembly, as described, on the cylinder 22, the transducer-element assemblies may be slid over the cable ll and electrically connected to the proper conductor pair 15 at the desired location. Another layer 27 of plastic or other illing may then be applied to secure the cylinder 22 on the cable lll, and to provide a tapered end Afor the assembly. Finally, a jacket 29 of rubber or rubber-like material, such Aas neoprene, may be appliedy over the entire device and faired into the cable jacket 18, as suggested in the drawing.

When the cable means l1 is of substantial length, it becomes important that the electrical parameters of all conductor pairs iii-l5', etc., be substantially the same. This may be readily achieved by making sure that all lines l5-15 are of substantially the sarne length, as suggested in Figs. 3 and 4. ln Fig. 3, I show al1 lines to terminate at the far end of the cable in an open circuit condition, as by casting the end of the cable in a block of insulating material, such as a block of plastic 31. Alternatively, all lines it-l5', etc., may be terminated with their characteristic impedances as suggested in Fig. 4, where the impedances 32 (labeled Zo) close each line and are cast in a single block 33 for ruggedness.

It is desirable that the overall density of the hydrophone unit 1d, when assembled on the cable 11, shall be kept to a minimum, consistent with structural rigidity. To this end, the pressure-,release means 26 may be of substantially greater volumetric proportions than those shown in the drawings, so as to render the hydrophone unit lil more neutrally buoyant. However, in the form shown, l have provided iioat members, as at 14, to irnprove the neutrally buoyant characteristic of the hydrophonic cable as a whole. rifhe float means 14 may cornprise a cylindrical shell 35, tapered at one end 36, and with a hub 3'7 smoothly to ride the cable sheath 1S. The shell 35 may dene an annular air pocket 38, providing the desired buoyancy, and resilient washer means 39 may assure concentric mounting of the shell 35 on the cable il. l have shown a cap member 40 ttng the open end of the shell 3S and including a hub 4l riding the cable sheath 18. A jacket of rubber or rubber-like material 42 may encase the buoy structure 14, so as to protect the same against damage in handling. I prefer that external dimensions of the buoy and hydrophone units shall be approximately the same in order to improve the ease of handling on board ship, as well as for uniformity of aunearance.

In Fig. 5, I illustrate an alternative hydrophone-unit construction wherein an annular air pocket 45 provides the means for pressurerelease internally of the transducer means i6-4?; like the transducer means 19--9' of Fig. 2, the transducer elements d6- 47 may be twoseries-connected, toroidally wound, magneto-structiveunits. I have shown the air pocket 45 to be delined by the cylindrical shell 43 upon which the mmebers 46--47 and their potting i9 are supported. The cylinder 48 may be spaced from the cable 11 to the desired extent, as determined by a 'Flange 50 on an end ring 51, and a further air pocket 52 may be provided at cach end of the assembly by conical end pieces, such as the conical cap 53, tting over the flange ring 51 and including a hub 5d riding the sheath of cable 1l. As before, a jacket 55 ot rubber or rubber-like material, such as neoprene, may encase the entire assembly so as to retain the same and so as to provide against damage in handling.

ln Fig. 6, l illustrate an alternative oat const'ruction having greater flexibility than that illustrated in Fig. 2. In the arrangement of Fig. 6, a corrugated metal bellows or sleeve 56 is held in radially spaced relation with the cable sheath 57, by means of rigid end caps; each end cap may comprise a conical member 58 on a sleeve 59 riding the cable sheath 57. A jacket Gil of rubber or .rubber-like material may be applied over the entire oat unit and taired to the cable sheath to provide proteclion against damage in handling.

it will be appreciated that I have described extremely rugged hydrophone cable constructions, which may not only provide great resistance to damage in handling but which also possess enough inherent flexibility to permit handling with conventional cable rigs, such as drums and ship-board cable-paying apparatus. The construction lends itselt` to relatively simple fabrication, and the low impedance characteristics of the magneto-strictive transducers d attractive from the standpoint of use in arrays extending for great distances.

While l' have described the invention in detail for the preferred terms shown, it will be understood that modifications may be made within the scope of the invention as in the claims which follow.

l claim:

l. An electro-acoustic array comprising a continuous elongated tension cable, a plurality of hollow generally cylindrical radially strictive members spaced along said cable with said cable passing continuously through said members, supporting means coaxially supporting each of said members on said cable, means carried by each said cylindrical member and electrically responsive to transient radial stressing thereof, said cable including a plurality of elongated electrical conductors insulated from each other and passing through said cylindrical members, one of said conductors being connected to the electrically responsive means associated with one of said cylindrical members, and another of said conductors being connected with the electrically responsive means associated with another of said cylindrical members.

2. An array according to claim 1, in which said supporting means includes a potting of incompressible material.

3. An array according to claim l, in which said supporting means includes a circumferentially extending layer of pressure-release material intermediate said cable and each strictive member and substantially longitudinally cocxtensive with said members.

4. An array according to claim l, in which said supporting means comprises an elongated hollow cylinder of diameter exceeding the cable diameter and spacer means radially spacing said cylinder from said Acable at spaced points therealong so as to define within said cylinder and about said cable a pressure-release volume.

5. An electro-acoustic array comprising a continuous elongated multifconductor electric cable with a continuous fiexihle tension core, a rigid cylinder supported by and coaxially surrounding a continuous part of said cable, an annular radially strictivc member supported by and coaxially surrounding said cylinder and in radially spaced relation therewith, means electrically responsive to transient radial stressing of said annular member and con- -ibed render the hydrophone cable particularlyY nectcd to an electrically conductive part of said cable, and a layer of sound-transmitting material in intimate soundtransmitting relation with said annular member and encasing said cable and said member at the point of axial overlap with the cable.

6. An electro-acoustic array according to claim 5, in which pressure-release means are provided between said radially strictive member and said cylinder.

7. An electro-acoustic array according to claim 5, in which pressure-release means are provided between said cylinder and said cable.

8. An electro-acoustic array, comprising a continuous elongated multi-conductor cabie with a tension core, a plurality of cylindrical hydrophones enveloping and coaxially supported by spaced continuous parts of said cable and electrically connected to different conductors in said cable, a plurality or' hollow cylindrical members enveloping and coaxially supported by other spaced continuous parts of said cable and radially spaced from said cable, and means sealing the ends of said cylindrical members to said cable, whereby said array may be neutrally buoyant.

9. ln an electro-acoustic array, a continuous elongated multi-conductor electric cable, and a plurality of toroidally Wound annular magnetostriction transducers electrically connected to and enveloping and coaxially supported by said cable at spaced points, said cable extending continuously through said transducers.

l0. An array according to claim 9, in which said transducers are potted to said cable.

l1. In an electro-acoustic array, a continuous elongated multi-conductor electric cable with a continuous tension core, a plurality of reinforcing cylindrical sleeves enveloping and coaxially supported by spaced parts of said cable, a plurality of annular electro-acoustic transducers enveloping and coaxially supported by each sleeve and electrically connected to said cable, and insulating means enveloping said transducers and each of said sleeve and sealing the same to said cable.

12. An array according to claim 11, and including reinforcement flange means carried by each sleeve and between the transducers around each sleeve and extending circumferentially and radially outwardly of said transducers.

13. in a device of the character indicated, a continuous elongated multi-conductor cable, a plurality of axially spaced taps to independent conductors of said cable, a rst hollow generally cylindrical radially strictive member coaxially surrounding said cable at one of said taps, a second hollow generally cylindrical radially strictive member coaxially surrounding said cable at another of said taps, means associated with each said cylindrical member and electrically responsive to transient radial stressing thereof and connected respectively to said one and to said other of said taps, and means circumferentially uniformly consolidating said members and said last-dened means to each other and to said cable, whereby the assembled device may have the full tensile strength of the multbconductor cable alone and yet may also be stored on a drum and otherwise handled as readily as the cable alc-ne.

An electro-acoustic array, comprising an elongated continuous multi-conductor electric cable with a continuous flexible tension core, a rigid cylinder supported by and coaxially surrounding a part of said cable, circumferentially extending rigid reinforcement means extending radially outwardly of said rigid cylinder at longitudinally spaced locations to define therebetween a circumferentially extending outwardly open groove, and a cylindrical radially strictive member within said groove and potted thereto and electrically connected to a conductor of said cable.

References Cited in the le of this patent UNITED STATES PATENTS 793,896 Mundy July 4, 1905 1,470,733 Hayes Oct. 16, 1923 1,584,613 Comstock May 11, 1926 2,325,199 Woods July 27, 1943 2,389,241 Silverman Nov. 20, 1945 2,431,846 Thuras Dec. 2, 1947 2,440,903 Massa May 4, 1948 2,551,417 Carlisle May 1, 1951 2,592,780 Woods Apr. 15, 1952 2,622,691 Ording Dec. 23. 1952 

